This invention relates to an electronic musical instrument and, more particularly, to a digital type electronic musical instrument capable of producing an excellent tone color effect by changing filter characteristics discontinuously with the lapse of time from the start of generation of a musical tone.
For obtaining a musical tone which is as close a simulation of a natural musical tone as possible, it is considered disadvantageous to have the ratio of each harmonic remain unchanged with the lapse of time. It is accordingly desirable to have characteristics of a filter used in the electronic musical instrument suitably change with the lapse of time from the start of generation of the tone and thereby provide the tone color of the musical tone with subtle variations. In electronic musical instruments, however, variations in the filter characteristic have been realized only by sliding the cut-off frequency with a resultant parallel transfer of the filter characteristic. The variations in the tone color achieved by this arrangement are far from being satisfactory.